Industrial naphthalene operations

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Industrial Naphthalene Operation Instruction (SJ-005) 1. Scope This instruction stipulates the operating methods of the company's industrial naphthalene production equipment. Suitable for industrial naphthalene distillation operations. 2. Reference standards, quality requirements 1. Industrial naphthalene (GB/T——6699——1998) Indicator name: Excellent product, first-class product, qualified product, white appearance, reddish or yellowish powdery flake crystal is allowed, crystallization point, ℃ is not less than 78.378.077.5 non-volatile matter, % is not more than 0.040.060.08 ash content, % is not more than 0.010.010.02 Note: a. Non-volatile matter shall be subject to factory inspection data. b. When supplying industrial naphthalene liquid, the non-volatile content index shall be specified by both the supplier and the buyer. 2. Dephenolized oil: Contains naphthalene ≤ 10% 3. Washing oil: Containing naphthalene ≤ 5% Special cleaning oil for absorbing benzene, containing naphthalene ≤ 5.0% (m/m) ； 230～270℃ Distillation volume ≥65% (V/V), moisture ≤1% Note: The moisture index is not used as a basis for quality assessment, and the excess part is used as a pricing factor. 4. Raw material requirements: Washed with triple mixed oil: Contains phenol ≤ 0.5%, contains naphthalene 45 ~ 60% 3. Overview of the process: The washed triple-mixed oil after washing and dephenolization is heated to 70---90°C in the raw material tank. It is sent to the preheater by the raw material pump to exchange heat with industrial naphthalene steam to 190±5°C and enters the distillation tower. The phenolic oil steam at the top of the initial distillation tower is cooled to 50--60°C by the phenol oil cooler, and then passes through the phenol oil oil-water separator and enters the phenol oil reflux tank. Part of it is refluxed to control the temperature at the top of the distillation tower, and the other part is fully flowed to the phenolic oil tank. The naphthalene wash oil at the bottom of the primary distillation tower is extracted by the primary tower hot oil pump. Part of it is heated to 250--265°C by the tubular furnace and returned to the bottom of the primary distillation tower. The heat is supplied to the primary distillation tower through hot oil circulation, and the other part enters the rectification tower. Industrial naphthalene is extracted from the top of the distillation tower. The naphthalene vapor at the top of the tower exchanges heat with the three-mixed feed oil and is cooled to 100-120°C by the evaporation cooler. It then flows to the industrial naphthalene reflux tank. A part of it is used for reflux at the top of the distillation tower. The full flow part enters the industrial naphthalene receiving tank and is crystallized by a rotating drum, sliced ​​and packaged. The washing oil at the bottom of the distillation tower is extracted by the hot oil pump, and part of it is heated to 270--300°C by the heating furnace and returned to the bottom of the distillation tower to supply heat to the distillation tower in the form of hot oil circulation. The other part is cooled to 50--70°C by the washing oil cooler and enters the washing oil tank. 4. Industrial naphthalene distillation operating procedures (method) 1. Process control indicators and operating indicators 1) Industrial naphthalene distillation process control indicators: Washed triple blend oil containing naphthalene: 45--60% ； Contains phenols: ≤0.8% naphthol oil contains phenol: ≤5% ； Contains naphthalene: ≤10% washing oil contains naphthalene: ≤5% industrial naphthalene crystallization point: ≥77.5℃ 2) Industrial naphthalene distillation operation indicators Item indicators The top temperature of the initial distillation tower is 170~190℃ The hot oil temperature of the initial tower is 242±5℃ The feed temperature of the initial tower is 190±5℃ The reflux liquid temperature of the preliminary distillation tower is 50~70℃ The gas phase temperature at the bottom of the initial distillation tower is ≤0.07Mpa (gauge pressure) The feed volume of the initial tower is 0.5~1.8m3/h The top temperature of the distillation tower is 215±5℃ The hot oil temperature of the distillation tower is 260~290℃. The feed temperature of the distillation tower is 220±5℃. The gas phase pressure at the bottom of the distillation tower is ≤0.01Mpa (gauge pressure). The feed material of the distillation tower is 0.5~1.5m3/h. The temperature of industrial naphthalene after cooling is 100~120℃. The temperature of the washing oil after cooling is 50~70℃. The temperature of the dephenolized oil after cooling is 50~70℃. 2) In-process flow sample analysis and inspection. Top analysis content analysis. Washed three mixed oils contain phenol and naphthalene. Distillation test 1 time/shift industrial naphthalene. Flow sample contains naphthalene 4 times/class industrial naphthalene tank sample. One tank wash oil flow sample contains naphthalene and distillation test 2 times/shift. Wash oil tank sample contains phenol and naphthalene. Distillation test 1 time/bendol oil flow sample contains phenol and naphthalene. 2 times/bendol oil tank sample contains phenol and naphthalene. Distillation test 1 time/shift 2. Preparation before driving. 1) Check whether the water, electricity, steam and gas systems meet the driving conditions and requirements. 2) Check whether the equipment, pipelines, instruments, and safety facilities belonging to the system are intact and complete. The equipment, pipelines, and valves that are parked for maintenance must be tested for quality as required, and the leak test must be qualified. 3) Check the direction of the pipeline and whether the door is opened and closed correctly. 4) Use steam to purge the pipeline to ensure smooth flow and no leakage, and purge the route: ① Initial distillation system a. Raw material pump inlet → Raw material tank return pipe → Raw material tank primary tower raw material inlet → Preheater → Raw material pump outlet → Traffic pipe raw material pump inlet → Raw material return pipe → Raw material tank b. Dephenolized oil returns to the front of the tower valve → Dephenolized oil reflux pump outlet → Traffic pipe return pump inlet → Circulation pipe → Unwashed three-mix oil tank c. Primary tower hot oil pump outlet → Primary furnace convection Section, radiating section → initial tower external circulation pipe → initial tower hot oil outlet of unwashed three-mixed oil tank → initial tower hot oil pump inlet → traffic pipe initial tower hot oil pump outlet → initial furnace convection section, radiant section → initial tower external circulation pipe → unwashed three-mixed oil tank refined tower raw material inlet → initial tower hot oil pump outlet → circulation pipe in front of the tower → unwashed three-mixed oil tank dephenolized oil condensation cooler outlet → oil-water separator ② Distillation system a, distillation hot oil pump outlet → distillation furnace convection section radiant section → distillation tower external circulation pipe → unwashed three-mix oil tank hot oil outlet of the fine tower → hot oil pump into the fine tower → traffic pipe hot oil pump outlet of the fine tower → convection section of the fine furnace → radiant section → external circulation pipe of the fine tower → outlet of the hot oil pump of the unwashed three-mix oil tank → washed oil cooler → washed oil tank (or unwashed three-mix oil tank) b. Industrial naphthalene refluxes into the Tava door → Reflux pump outlet → Traffic pipe reflux pump inlet → Industrial naphthalene reflux column outlet before cutting → Intermediate tank c. Industrial naphthalene carburetor oil outlet → Industrial naphthalene reflux tank 5), Steam sweeping precautions ① Use a bypass when sweeping the sight glass. ② Except for ignition, steam is strictly prohibited from entering the tower. 6) Preparation of reflux liquid ① Heat the dephenolized oil reflux liquid to 50~70℃. ② Industrial naphthalene reflux column, heated to 100~120℃. 7) Prepare the supply and storage of raw materials, products. 3. Start-up process 1) Add washed three-mix oil to the primary tower and fine tower through the temporary feeding pipe, and add the input amount to the liquid level of 2m. 2) The initial and finishing furnace points are less than 200℃, and the furnace temperature is less than 200℃. 3) Start the hot oil circulation pump of the initial tower and fine tower, and adjust the circulation to 30-40m3/h. 4) Gradually increase the circulating oil temperature at a rate of 30 to 50°C per hour. 5) When the feed plate of the initial tower approaches 100°C, be prepared for feeding and refluxing. 6) When the feed plate is close to 120°C, start the raw material pump, open the tower entry door and feed material to the initial tower. 7) Observe the temperature at the top of the tower. When it rises to 150°C, start the reflux pump to reflux. 8) When the feed plate of the distillation tower is close to 120°C, start the initial fine feed and open the tower entry door to feed the fine feed. 9) Observe the temperature at the top of the tower. When it is close to 210°C, start the industrial naphthalene reflux pump to reflux. 10). Open the washing oil extraction door and extract the washing oil. 11) Adjust parameters until the product is qualified. 4. Parking process. 1) Stop the tube furnace, purge the furnace, and open the tube furnace flap. 2) Stop the raw material pump of the initial tower, close the raw material inlet door, purge the pipeline, and then stop the steam. 3) Gradually reduce the reflux in the initial tower and maintain the tower top temperature not exceeding 175°C. 4) When the temperature at the top of the tower is lower than 150°C, stop the reflux, close the reflux inlet door, and purge the pipeline. 5) Stop the initial fine feeding, close the tower inlet door, and purge the pipeline. 6) Gradually reduce the reflux of the fine tower and maintain the tower top temperature not exceeding 210°C. 7) When the temperature at the top of the tower is lower than 180°C, stop the reflux, close the reflux inlet door, and purge the pipeline. 8). Wash oil tangentially and unwash the three-mix oil tank. When the liquid level is lower than 0.3m, stop washing oil extraction and purge the pipeline. 9) If the production is stopped for more than two days, the materials in the tower need to be pumped to the raw material tank through the initial tower circulation pump. 5. Normal operation. 1) According to technical regulations, control the feed product flow rate of the primary distillation tower and rectification tower, the liquid level at the bottom of the tower, and the temperature and pressure of each control point. 2) Control the material temperature of heat exchangers, industrial naphthalene condensation coolers, dephenolizing oil coolers and washing oil coolers according to operating standards. 3) According to the quality and output of industrial naphthalene and dephenolized oil, control the reflux volume of the distillation tower and the top of the primary distillation tower, set the qualified hot oil circulation temperature, and control the quality of the washing oil. 4) To maintain a material balance in the two towers, the input amount of raw materials must be balanced with the total output. The feed volume of the two towers must be stable. 5) The industrial naphthalene flow crystallization point is measured every hour. If the crystallization point reaches the standard, the product will be put into the qualified industrial naphthalene product tank, and the unqualified industrial naphthalene will be put into the unqualified industrial naphthalene product tank or returned to the intermediate tank. 6). Make original records of this position on time. 6. Treatment of unqualified products 1), industrial naphthalene ① Flow sample is unqualified: Adjust operating indicators in a timely manner. ② Substandard products during driving: Return to intermediate tank blending until qualified. ③ Industrial naphthalene product tank failed inspection: Blend until qualified or return to intermediate tank. 2) Washing oil ① flow sample is unqualified: Adjust operating indicators or intermittent emissions in a timely manner. ② The tank sample is unqualified: Blended until qualified. 3). Removal of phenolic oil ① The flow sample is unqualified: Adjust operating indicators in a timely manner. ② The tank sample is unqualified: Blended until qualified. 7. Special operations 1), power outage: Stop the furnace immediately and purge steam into the furnace to cool down. 2), tower quality increases: The heating system should be cooled down appropriately. If there is backflow or water in the raw materials, it should be dealt with in time. If the cooling water is found to be insufficient, the amount should be reduced in time. 3), tower liquid cooling: Appropriately cool down, reduce the return flow or reduce the processing capacity. 5. Relevant systems: "Shift handover system", "Itinerant inspection system" and "Equipment management system".